SERG have successfully linked Albany to Mt Barker, as well as extending the APRS coverage down in the south west. Plan is to possibly link Mt Barker back up to Katanning. Thanks to Rob and the crew down south.

WARG have recently been doing some refurbishment up at Tic Hill, consisting of new antennas, new coax cable runs, new solar panels and regulators, new batteries, refurbishment of repeater, APRS and telemetry monitoring of battery voltage, and soon to install a wind generator. This site has also had increased WAFreenet upgrades including IP Surveillance cameras, 5GHz data links and VOIP capabilities.

will be recovering/repairing/replacing the repeater at RMS at Mt Saddleback in the comming weeks thanks to William who will be working in the area on a commercial basis. This should see all services at RMS, including the WIA news link back to RAP restored.

Peter VK6FUN has been doing extensive work on the APRS network with BBR getting re-instated up at rolleystone soon, and APRS coverage expansion out towards Kalgoorlie, starting with Northam, York and Kellerberin links. Thanks to VK6TNC for offering to host an APRS digipeater link in to Tic Hill from the East.

HARG have a new APRS digipeater up at the club rooms. keep an eye/ear out for VK6AHR. There has been a recent uptake of APRS throughout the South West, particularly the Perth area, so this new APRS digi should assist in some void areas to the SE of Perth and beyond. It’s great to see so many more people showing an interest in APRS. This is largely due to “Beacon in a box” units being offered by BigRedBee and Byonics, and VK6FUN distributing 10 Argent Open Trackers.

VK6RAP is due for an overhaul of it’s antenna and feeders. Date is penciled in as 11th and/or 12th September. Please feel free to come and help out.

December is penciled in as a “Weekend at Cateby” to do a major overhaul of most of the site. Works will consist of guy replacement, antenna/feeder refurbishment/replacement, new radios, new batteries, new solar cells, new DC distribution etc etc… Let us know if you’re keen for a great weekend away.

WARG is currently costing up the replacement/upgrade to the entire WARG Repeater network which will consist of new repeaters, new controllers and refurbishment of Antennas and feeders. A 300m roll of LDF5-50 has been purchased for Rolleystone, and considerations for repeater upgrades has come down to the Icom IC-FR5000/6000 series and the Spectra MX920 series. Negotiations are currently underway to secure the supply/support and sponsorship of the new network. Recovered equipment will either be refurbished and used for spare repeaters, expanding the network even further, or possibly even sold to raise more funds for more new equipment.

With the upgrade to the network we should see improved performance of all of our repeaters, expansion of the WIA news broadcast, new features such as permanent linking between some site, as well as the ability for a user to connect to a particular site manually/remotely.

Expansion of the network is being explored to the North up to Geraldton, and to the East to Kalgoorlie. Path profiling, Site Surveys, and site access/agreements are currently being looked at.

Ive been working on some google map plots which some of the WARG members have seen. Eventually they will incorporate all of the APRS and voice, current and future links. Keep an eye out in the files section here: http://groups.google.com/group/wahams/files

If anyone is aware of more network activities, or would like to offer ideas, equipment or hosting facilities, please let me know.

73′s

Heath VK3TWO / VK6TWO

WA Repeater Group – President
VK6 DSTAR coordinator
VHF Group – Vice President
Hills Amateur Radio Group – Vice President
Wireless Institute Civil Emergency Network – Technical Officer
Wireless Institute of Australia – Advisory Committee (VK6)

SpoOkTech Engineering
+61 404 893 178 begin_of_the_skype_highlighting              +61 404 893 178      end_of_the_skype_highlighting
spooktech@gmail.com
Skype: spooktech
www.spooktech.net

Location: Perth Hills.

Coverage: Perth Metro Area.

googlemap

http://warg.org.au/wordpress/?page_id=39&album=18

Anthony here, quick update on today’s work at Roleystone.

The UHF repeater VK6RUF was found to have almost no output power (no doubt the cause of the poor performance) and was removed, I have the transceiver for repair and will reinstate as soon as fixed, hopefully later this week.

Other antennas were checked and the 2m repeater & diplexer/cavities spec-checked to try & correct the intermittent noise problem. (One suspect coax connector was replaced, we should continue to monitor the repeater performance to see if any improvement). The 6m voice repeater was also checked, all looks OK.

The batteries were removed, cleaned and refitted, allowing timber reinforcing to be placed underneath (not quite enough timber for the whole set, job will be completed next time). The DC system was checked and the power supplies readjusted to compensate for voltage drop (due to diodes in series), so the battery/system
voltage is ~13.6V.

Some of the cells are starting to show signs of age, and while we can probably count on another year or two from these, we need to start looking around for replacements – the existing ones are sealed gel types, heavy duty, around 500AH per cell – if anyone can find some disposal ones like these in reasonable condition, we
are definitely interested! (If the price is right…)

More work is planned in November (date TBA) including the packet system overhaul, Bob VK6ZRT has volunteered his expertise to carry out this work (and hopefully train a few others of us in the ongoing care & feeding of VK6BBR).

Thanks to all who attended today: William VK6KWT, Cliff VK6LZ, Andrew VK6VCG, Matthew VK6KMC, Dennis VK6KAD, Jim VK6JIM, Anthony VK6AXB. My apologies if I have forgotten to mention anyone, all efforts are sincerely appreciated.

BR & 73,
Anthony VK6AXB.

It will be held at the Darling Range RSL Hall, 35 Canning Road, Kalamunda, starting from 11.00am. (See map below for directions)

There will be a presentation from Icom representatives and then a practical demonstration.? They will also be available for questions and assistance so please make sure you bring your DSTAR radios along.

We will be having a sausage sizzle for lunch and John Tower will be there with some DSTAR equipment for sale!

Please come along, it will be good to see you all there.

Please pass this e-mail onto anyone that would be interested.

For further information please contact myself, VK6FZUK on 0414 533 244.

Regards, Danny Ainsworth – VK6FZUK.

googlemap

Having spent over 40 hours getting the D-star 2M duplexer ready has been a most interesting exercise.

The 6″ cavity filters we have had to be modified to allow them to work as notch filters and is bassed on the original design (4″ filters) by W1GAN JOHN J BILODEAU form an article in QST July 1972. What worked for the 4″ cavities had to be fiddled with on the 6″ ones.

The filters have been finished and now I’m fine tunning the coax lengths that connect the filters together. This part of the design was never covered well in the original or later articles. The lengths were given but not the reasons for the lengths. The lengths as given work but not as well as should be achievable.

The tracking spectrum analyser that WARG bought a while back has been fantastic in converting the 6″ cavities. Without it I could have tuned the duplexer up but would not have been able to do it easily and would not have been able to get results that can be achieved with the analyser.

The analyser shows you not just pass and notch but the type of curves. This has shown the interaction with the cable lengths that give various shapes, various peaks and dips that indicated the overall design is not working as well as it can and should.

With out the analyser the pass loss can be as high as 2.5 dB while with the analyster it can be as low as 1.5dB. Okay only a dB but it all adds up. The overall notch depth can not be seen on the analyser as it will not show 70dB plus notch depth. Each cavity can be seen okay but what happens when they are all connected together?

I can work this out using the analyser’s sig gen and a receiver and will do so next.

The attached photos show the PCB (painted) boxes on top and the difference with the pass frequency when you connect two cavities together with incorrect cable lengths. Each cavity has a good pandpass but when connected cause the bouble hump….Working on it.

Will
VK6UU ]]> http://warg.org.au/wordpress/?feed=rss2&p=99 0 http://warg.org.au/wordpress/?p=98 http://warg.org.au/wordpress/?p=98#comments Sun, 20 Jul 2008 14:59:19 +0000 will http://warg.org.au/wordpress/?p=98 Some pictures of the new Walliston D-Star repeater site, courtesy of Will VK6UU have been uploaded to the WARG website.

See:? http://warg.org.au/wordpress/?page_id=39&album=13

I would also like to start up a DSTAR simplex net if anyone is interested. If anyone would like to take part, or anyone in VK6 who has DSTAR capabilities, they can please email me VK3TWO/6.

I currently have gear capable of 2m, 70cm and 23cm and would like to make
use of them!

Thanks.

Heath – VK3TWO/6
VK6 DSTAR Coordinator

A maintenance visit to tic hill (Redhill) VK6RTH was carried out today, (08.05.08)? mainly to check on the electrolyte levels in the 2 volt wet cells and general visual of the site.

This was carried out by Bob VK6POP(with 4 x 4 vehicle) and myself.

As usual we were escorted through the Quarry (mine site) by the site owners (Hansons), although they were busy at the time. They appreciated the Cake for morning tea which we leave as a thank you for their assistance.

Bob topped up the large wet cells with distilled water which had gone down by a about a third (in the min/max safety area)in each cell since October 07, this took approx 1 litre each, and cleaned the terminals
which showed signs of salt build up.

I checked the SWR on the Antennae cables (70 cm = 1.4/1 and 2m 1.3/1) which appear to use the dual bander. The Digipeater could not be checked as we did not have a BNC connector for the Antenna Analyser with us.

I am mystified as to what exactly is on the Tower(s) for example what is the dish? and square box half way up the main tower for ? is it wifi and whose is it?

I know about the 4 x 4 club receiver and LIPD Xmitter which appears to be working (we also topped up their wet cells).

There are also three unused co-axes – one open circuit and two with reasonable SWR.

The Solar cells were feeding 5 Amps during bright sun. The batteries each showed 2.2 Volts.

A visual check of the tower did not show up any problems. The water leak repair to the “Bunker” last October seems to have held with no evidence of water.

73 Cliff VK6LZ (Site Manager)

Attached is a concept for the very important antenna installation on the Walliston tower. There may be another concept idea but I have not seen such as of yet. So to kick things off please have a read and comment.

Will
VK6UU

Walliston RF concept

Will VK6UU

The antenna layout on the Walliston tower can be designed in several different ways, each with its own pros and cons.

The concept presented here relies on separate antennas for each band and split antennas, i.e. separate antennas for receive and transmit, except for the 70cm digital repeater and the simplex 23cm high data rate gateway.

This design is expensive in that it uses more antennas (8) and more coax (8) and hence takes up more mast space, but most important offers several important advantages.

Antenna failure.

Antenna failure, replacement and testing only takes out one repeater. If a triband or dualband antenna fails for example it affects 3 repeater systems. Antennas can be easily isolated tested and replaced.

Desense isolation

Easier to achieve desense isolation with less reliance on duplexer performance. Good duplexer performance is difficult to achieve particularly on 2M. 70cm duplexers are cheap and don?t require as much isolation as 2M duplexers. 23cm duplexers are difficult to source. The antenna layout highlights this with only the 70cm repeater using a duplexer into a single antenna.

Below is a concept diagram of the Walliston site. It shows the antenna mast, which is 75? (23M) high along with the layout of the antennas. Yes there are a lot of antennas and yes there is more than one way to put together the antenna layout. The number of antennas could be reduced. This design uses split antennas on all systems except the 70CM digital repeater and the 23CM high-speed digital simplex system.

Split Antennas

Split antennas means one for receive and one for transmit for each duplex repeater, rather than a duplexer feeding one antenna. This offers one major advantage, less filter isolation is required (cavity filters) and zero desensing is much easier to achieve.

What type of antenna to use?

Folded dipoles and in particular the ones you see on commercial installations are cheap, broadband, DC earthed for lightning protection, low SWR (1.2 or better), robust, come in a wide frequency range, can be custom made if required (e.g. 23cm) and can be stacked (more than one) to produce increased gain. And these antennas are designed to work side mounted on a tower, which is the type of installation we are looking at. Side mounting also produces 3dB gain, which is ideal, as the Walliston site should direct most of the signals to the West.

Variations

Due to the number of antennas and the number of coaxes required in this design there are some options to reduce this. For example the 2M receiving dipoles (2 of) could be phased together (3dB gain) connected to one coax and then split via a low gain RF amp at the bottom of the tower, giving two antenna feeds. Or only one dipole could be used (to save antenna space) and split as described.

The 4-dipole arrays on 23cm and 70cm could be reduced to 2 dipole arrays. It all depends on what the tower can support.

The diagram is only roughly to size but a to scale diagram can be produced to give us a better idea of the antenna space taken.

Walliston tower configuration

I hope this document encourages discussion and more ideas. The antenna installation is one important (if not the most important) aspect of this complex installation. If we wish to achieve the very best performance RF wise then considerable engineering excellence needs to be our number one goal.